Igniter



All@ 45 1959 R. REDDYl 2,897,649

Y IGNITER Filed July 3. 1956 2 Sheets-Sheet 1 R. REDDY Aug. 4, 1959IGNITER Filed July :5, 1956 2 Sheets-Sheet 2 INVENTOR.

M jf HTTEA/FYS United States Patent() 2,891,649 IG1-1rrERY Robert Reddy,Pasadena, Calif., assignor to the United States of America asrepresented by the Secretary of the Air Force Application July s, 1956,serial No.' 595,800

' 6 claims. (c1. so-'3932) This invention relates to an igniter for acombustion apparatus and, more particularly, to a multistage igniterprimarily for use with hypergolic propellants.

Combustion chambers of rocket engines, for example, require a flamehaving high heat intensity for igniting the fuel propellant. lf a ame ofthe required high intensity 2,897,649 Patented Ang. 4, 1.959

y having'pistons 22 'and 23 movable therein, respectively were producedrapidly, inthe igniter, there would be y,

danger of an explosion in theA igniter. If an attempt were made tocreate such a large ame suddenly in the combustion chamber, there' alsoexists the possibility that the fuel in the combustion chamber would notignite and an expensive procedure would result in ultimately ignitingthe fuel by creating a flame ofv high heat intensity in the combustionchamber. The igniter of the present invention creates the desired llameof suicient intensity by igniting the propellants gradually rather thanrapidly.

An object of the present invention is to provide an A nozzle 24 isdisposed on the end of the piston 22, which is .shown in cross 'sectionin Fig. 2. It will be understood that'the movement ofthe parts of thepiston y22 and the cylinder 20 also `applies to the cylinder 21 and thepiston 23, which are not shown in cross section. A passage 25 extendsthrough the center of the piston 22 and a plurality of radiallyextending passages 26 is in connection with the passage 25. As isreadily seen, the radial passages 26 are spaced along the passage 25.

As the pressure in the primary ignition chamber 11 increases due to thecombustion therein, the pressure is transmitted into the secondaryignition chamber 12`and against the faces of the pistons 22 and 23,which are in communication with the secondary ignition chamber 12.

' This pressure increase results in the piston 22 moving igniter thatproduces a substantial ignitiony ame therein at a gradual rate. d

Another object of this invention is to provide an igniter that projectsits llame into a Vcombustion chamberwhen the flame has a suicientintensity to ignite the fuel in the combustion chamber.

Other objects will be readily preceived from therfollowing description.l

This invention relates to an igniter having two ignition chambers incommunication with each other. Puel is initially supplied to the smallerof the'.two ignition chambers by suitable'means for ignition therein. Asthe pressure resulting from the' combustion in the smaller chamber intransmitted to the larger ignition chamber, fuel is supplied to thelarger chamber by suitable means in response to this pressure increasein the second chamber. This fuel, of course, is ignited in the largerchamber.

The attached drawings illustrate preferred embodiments of the invention,in which against the force of a spring 27, which is disposed betweenthe'cylinder 20 and the piston 22. As the piston 22 movesoutwardly'against the force of the spring 27, the outermost of thepassages V26 communicates with an annular port or groove 28 in the wallof the cylinder 20. The annular port 28A is supplied with Ithe fuelpropellant through a tube 29 that is connected to the fuel source (notshown). It will be understood that an annular port inthe wall of thecylinder 21 isY connected to an oxidizer source (not shown). VV.As theoutermost ofthe passages 26 communicates with the annular port 28, thefuel passes therethrough into the passage 25 and through the nozzle 24into' the `secondary ignition chamber 12. Similarly, the' oxidize'rpasses through the outermost of the radial passages in lpiston 23 1andthrough the central passage and nozzle into the Vsecondary ignitionchamber 12. EIt will be understood 'that the size of the radial passagesin the piston'23 is in proportion to the size of the radial passages 26in the piston 22 `in the same ratio as desired between the mix# ture ofoxidizer and fuel to produce combustion. This Fig. 1 is a sideelevational view of the igniter'of the present invention;

Fig. 2 is a sectional view taken along thev line 2-2 Fig. 1; and

' Fig. 3 is a sectional view showing a modification ofthe igniter ofFigs. 1 and 2.

' VReferring to the drawings and particularly to Figs. 1

and 2, there is shown an igniter housing 10 including-a primary ignitionchamber 11 and a secondary ignition chamber 12 in communication witheachother. A fuel, such as a hypergolic propellant,is,supplied to theprimary ignition chamber 11 through a tube 14. The fuelv propelprimaryignition'chamber 11., .The-heating element 16 has f depends 9,1;thefgrrce ofthe Sarina .33 ,t

mixture ratio, of course, depends on the oxidizer and the fuel employed.Y'

lThe heat generated i'n the primary ignition chamber V11 is transmittedinto the secondary chamber 12 where the fuel entering the secondarychamber 12 through the nozzle 2 4is ignited. This, of course, furtherincreases the pres; sure exerted against the face of the piston 22 tomove the piston 22 further outwardly whereby more of the passages 26communicate with the annular port 28 to increase the supply of fuelthrough the rnozzle 24 to the secondary ignition chamber 12. lit will beunderstood that the' piston 23 s likewise exposed to the pressure fromthe chamber 12 and supplies the desired proportional quantity of theoxidizer through its nozzle (not shown).

The housing 10 has ra passage 30, which connects the secondary ignitionchamber 12 with a combustion chamber 31 of a rocket engine, for example.A poppet valve 32 controls the passage 30 to prevent communicationbetween the secondary ignition chamber 12` and :the combustion chamber31 until a predetermined pressure exists Within the secondary ignitionchamber12. The existence of this 4predetermined pressure within thesecondary ignition chamber 12 indicates a ame has been created suicientto ignite the propellants in the combustion chamber 31. -The poppetvalve 32 is held inits closed position by a spring 33 acting against aflanged member v34, which is secured to one end of a rod 35 on `theother end of which the poppet valve 32 is formed. The amountof forcerequired to open the poppet valve 32 i. Considering the operation of theembodiment of the present invention shown in Figs. l and 2, the fuel issup? plied through the tube 14 and the oxidizer through the tube 15-tothe primary ignition chamber 11 for combustion therein. The heatingelement 16- heats `both propellants vpi'iorfto their deliveryintothe'primaify ignition chamber 11... Since the quantity is small andy thepropellants'are heated; the propellants easiiypignife'nypergoncaty." Asp the primary ignition chamber 11- communicates with-both the secondaryignition chan'ib'erl 12 and 'the pistons 22 and 23, the pressure'created by the combustion in the primary chamber 11 is transmitted tothe secondary charnber 12 and the pistons 22 and 23'. sthispresSureinereas, the pistons 22 and 23` are 'forced outwardly Vin theirrespective cylindersf20 vand"2'1"to allow'commnication between theannular port and at least one of the radial passages. This supplies thefuel and oxidizer propellants to the secondary chamber 12;'where theyare ignited readily as they enter the secondary ignition cham ber 12 dueto the heat therein.

The additional combustion in the secondary ignition Ychamber 12 createsadditional pressure whereby the pistons 22 and 23 move to the fullextent of their travel and permit communication between theY annulargroove and all of the radial passages tosupply a larger'amount of thepropellants through the nozzles tothe secondary ignition chamber 12. Theincreasing'combustion resulting from the larger supply of propellantstothe secohdary lignition chamber 12 causes a further pressureincreasein the secondary ignition chamberjthis furtherv pressure increase in thesecondary ignition chamber moves lthe poppet valve 32 against the forceof thespring 33 to open the passage and the flame emerges from theigniter housing 10 into the combustion chamber v31 of the rocket .engineto ignite the propellants therein. It will be understood that the ow ofpropellants to the igniter is stopped upon ignition within thecombustion chamber 31 of the rocket engine; thisv reduces the pressureinthe secondary ignition chamber 12l and the spring 33' automaticallymoves the poppet valve 32 to close the passage 30 and prepare theigniter for a new cycle.A

A modification of the embodiment of Figs. l and 2 is shown inFig. 3where both propellants are suppliedito the secondary ignition chamberthrough a single piston and cylinder rather than through separatepistons and cylinders. The igniter housing 10' has both a primaryignition chamber 11 and a secondary ignition chamber 12' communicatingwith each other. Avtube 14' supplies a fuel propellant to the primaryignition chamber 11' while a tube 15 supplies an oxidizer propellant tothe primary ignition chamber 11'. .Both'of. these tubes are yWrappedaround :an electrical heating element 16.l

which is disposed within the igniter housing 10' to heat the propellantsprior to their delivery tothe primary ignition chamber 11. The heatingelement 16' haslwires 17 and 18 connected to a suitable source ofelectric power (not shown). The heating -element 16 and the tubes 14 and15 are insulated by suitable insulating v oxidizer source (not shown),alsoexte'nds through the 1' cylinder 40. A plurality of slantingpassages 43 connects the passage 42 and a plurality of slanting passages46 connects the passage 45 with the annular portion of the cylinder 40in which the annular piston 41 moves.

`A' spring 44, which is disposed between the wall of the cylinder 40 andthe pistonA 41, urges the piston141 to the position shown inFig. Srwherethe"v passages 43 and 46 are closed by the piston 41,. As the pressurein the secondary ignition chamber 12 increases due to the ignition ofthe propellants in the primary chamber 11', the pressure forces thepiston 41 against the spring 44 to open some of the passages 43. Thispermits fuel propellant to flow through the passage 42 and the passages43 and oxidizer propellant to iiow through the passage 45 and thepassages 46 into the secondary ignition chamber 12 where they areignited by the heat resulting from the initial combustion in the primaryignition chamber 11. This creates a pressure increase in the secondaryignition chamber that nally results in allk of the passages 43 and 46being opened to 'further increase the supply of fuel and oxidizerpropellants to the secondary chamber 12. This additional pressureincrease in the chamber 12 acts against the poppet valve 32' to overcomethe force of the spring 33' to open the passage 30' and allow the flame,which was created in the secondary ignition chamber 12', to enter thecombustion chamber 31. It will be noted that the passages 43 and 46 areslanted to direct the propellants in a jet type manner into thesecondary chamber 12. The size of the passages 46 is proportioned withrespect to the size of thepassages 43 in the same ratio as thedesiredmixture of oxidizer to fuel required to produce combustion.

, Thus, the operation of the modification of Fig. 3 is substantially thesame as, thatjdescribed vwith respect to Figs. 1 and 2 with thedifferencebeing that a single piston and cylinder are employed to supplyboth propellants to the secondaryl ignition chamber rather than twocylinders `and pistons. It also will be -noted that the nozzles of themodification of Figs. 1 and 2 have been eliminated by theslantingpassages 43 and 46. Y

l While the description refers to the employment-of a fuel propellantand an oxidizer propellant being heated to produce the ignition, it willbe understood that a spark could be relied upon to vignite the fuel inthe primary ignition chamber and a spark also couldrbe used in thesecondary chamber if the fuel employed were not of the type ignited fromthe heat caused by the ignition in the primary chamber. The onlyrequirement is that some type of means be employed for creating agradual rate of ignition of the fuel in the igniter housing and theflame not be released therefrom until it has sufficient intensity toignite the fuel within the combustion chamber .to which the igniterhousing is connected.

An advantage of the present invention is that it prevents an explosionin the combustion chamber until a satisfactory flame is available forigniti-ng the fuel therein. A further advantage of this invention isthat it creates a substantial dame but ignites the fuel gradually ratherthan rapidly. Still another advantage of this invention is that it isless expensive for starting'combustion in a combustion chamber sinceless fuelis wasted if there is a failure in the igniter housingvof thepresentinvention rather thanin a device having the starter ignition inthe combustion chamber per se.

For purposes of exempliication, particular embodi ,ments of theinvention have been shown and described according to the bestpresentunderstanding thereof. However, it will be apparent that changes andmodiiications in the arrangement and construction of the parts thereofmay be resorted to without departing from the true spirit and scope ofthe invention.

l. In combination, a combustionchamber, an igniter forthe combustionchamber including Aa first ignition chamber and a second Vignitionchamber in communica- -tioni with. eachl other, means to admit fuel tothe rst yignition. chamber, means to ignite the Vfuel in the rstignition chamber, means tosupp'ly fuel to the' second ignition chamberin response toY a pressure increase in the second ignition chamber `forignition in the second chamber comprising integrally formed fuel andoxidizer 'passage' meansand integrallygrooved piston meanshav ing aforward set of proportionally related, radially extending grooves incommunication between saidifuel and oxidizer passage means and saidsecond chamber to form a combustible mixture therein acted on by theheat generated in said first chamber and a plurality of rearward,radially extending grooves integrally formed in said piston means toprogressively increase the supply of combustible mixture formed in saidsecond chamber on movement of said piston means in accordance with theincrease of pressure of the combustion in said first chamber, and meansresponsive to a further pressure increase in the second chamber todirect the flame in the second chamber to the combustion chamber.

2. An igniter including a first ignition chamber, a second ignitionchamber in communication with the first ignition chamber, means to admitfuel to the first ignition chamber, means to ignite the fuel in thefirst ignition chamber, land piston means normally spring urged ltoclosed position movable in response to a pressure increase in the secondignition chamber to a progressively open position to initially supply aminimum of fuel and oxidizer to the second ignition chamber for ignition:in the second chamber and having radially extending conduits formedtherein in progressive communication with said -second chamber toprogressively increase the mixture of fuel and oxidizer therein inaccordance with the increase of pressure in said first chamber.

3. In combination, -a combustion chamber, an igniter for the combustionchamber including a first ignition chamber and a second ignition chamberin communication with each other, means lto admit fuel to the rstignition ch-amber, means to ignite the fuel in the first ignitionchamber, piston means movable in response to a pressure increase in thesecond ignition chamber to supply fuel to the second ignition chamberfor ignition therein, said piston means increasing ythe supply of fuelas the pressure in the second ignition chamber increases, a passageconnecting the second ignition chamber with the combustion chamber, andvalve means to control the passage, said valve means being responsive toa predetermined pressure in the ysecond ignition chamber to open thepassage to allow the name to enter the combustion chamber, said pistonmeans comprising a cylinder positioned adjacent one end of said secondignition chamber, an annular piston mounted within said cylindernormally urged to its closed position with one face thereof in opencommunication with the interior yof said second ignition chamber, Ianouter fuel `supply conduit and an inner oxidizer supply conduitincorporated in said cylinder, and a plurality of fuel-oxidizer conduitsintegrally formed in said piston in progressive open communication withsaid fuel and oxidizer supply conduits on progressive movement of saidpiston by a predetermined pressure within said second ignition chamber.

4. In combination, a combustion chamber, an igniter for :the combustionchamber including a first ignition chamber land a second ignitionchamber in communication with each other, means to admit fuel to the rstignition chamber, means to ignite the-fuel in the first ignitionchamber, means to supply fuel to the second ignition chamber forignition therein, means to control the supply means in accordance withthe pressure in the second ignition chamber whereby a pressure increasein the second ignition chamber increases the supply of fuel theretocomprising at least one resil-iently mounted, annularly disposed pistonnormally held in closed position with one face thereof communicatingwith the interior of said second ignition chamber and acted on by apredetermined pressure therein to move to open position, said pistonhaving fluid passages in communication with said supply means totransfer fuel into said second ignition chamber when said piston ismoved to open position, a passage connecting the second ignition chamberwith the combustion chamber, and poppet valve means to control thepassage including an elongated valve member integrally `formed on saidvalve means and having spring urged means on the other end :thereofnormally resisting the pressure within said second ignition chamberuntil the flame formed therein effects .a further pressure increaseabove a preset minimum, said Valve means being responsive to apredetermined pressure in the second ignition chamber to open thepassage to allow the flame to enter the combustion chamber.

5. An igniter including Ia main housing having a first ignition chamber,a second ignition chamber in communication with the rst ignitionchamber, means to admit fuel to the first ignition chamber, means toignite the fuel in the first ignition chamber, means to supply fuel tothe second ignition Ichamber for ignition therein, and means to controlthe supply means in -accordance with the pressure in the second ignitionchamber whereby a pressure increase in the second ignition chamberincreases the supply of fuel thereto comprising a cylinder incorporatedwithin said main housing adjacent to said second ignition chamber having4an outer annular passage extending therethrough and adaptable forconnection to a source of fuel propellant and an inner annular passageextending therethrough and adaptable for connection to -a source ofoxidizer and having a plurality of fluid passages, respectively,connecting said outer and inner annular passages with an annular portionof said cylinder interionly thereof, and an annular piston movablymounted within said annular portion adjacent to one end of saidplurality of fluid passages normally closing said passages in oneposition thereof and -gradually movable under a predetermined pressurewithin said second ignition chamber to a second, open position toprogressively open said huid ,passages and effect increasing iiow offuel and oXidizer therethrough into said second ignition chamber inaccordance with the pressure increase within said second chamber.

6. An igniter including a first ignition chamber, a second ignitionchamber in communication with the lirst ignition chamber, means to admitfuel to the first ignition chamber, means to ignite Ithe fuel in thefirst ignition chamber, piston means having nozzle means incommunication with said second ignition chamber and having .a pluralitytof spaced grooves movable therewith in response to' a pressure increasein the secondignition chamber to open communication between a supply -offuel land ioxidizer :and said second ignition chamber for ignition `inthe second chamber, said piston means progressively increasing thenumber of grooves formed therein in communication between the supply offuel and oxidizer in said second chamber to increase the supply of fueland oxidizer delivered thereto as the pressure in the first ignitionchamber increases, a passage connecting the second ignition chamber witha main combustion 'chamber or the like, and valve means to control theflow of -ame through Ithe passage, said valve means being movable to its'open position only on response to a pressure above a predeterminedpressure in the second chamber to lopen the passage to allow la flame ofsuicient heat intensity to enter the combustion chamber.

References Cited in the le of this patent UNITED STATES PATENTS2,683,963 Chandler July 20, 1954 2,707,479 rDhornann et lal May 3, 19552,775,865 Welch Jan. 1, 1957 2,847,826 Howes f.- Aug. 19, 1958 FOREIGNPATENTS 503,766 Germany July 26, 1930 719,946 Great Britain Dec. 8, 1954

